direct contrast investigations

Direct contrast investigations

In this group of investigations water-soluble contrast is injected via some form of catheter directly into part of the urinary tract.

All of these procedures may potentially introduce infection into the urinary tract and care should he take to use a sterile technique,

broad-spectrum antibiotics should be administered prior to the procedure.

Retrograde pyelography

This investigation aims to optimally opacify the pelvicalyceal system and ureter.

It usually follows an IVU with non functioning kidney further Improve demonstration of the collecting system, either when there has been inadequate demonstration of part

or all of the system with ivu when the IVU is normal but the abnormal laboratory findings

persist. It is occasionally used to demonstrate the lower end of an

obstructed ureter.

procedure The urologist positions catheters within one or both

ureters cystoscopically and the patient is transferred to the radiology department.

Under screening control 5-20 ml of a 150 strength water soluble iodine-containing contrast agent is injected via each catheter in turn.

It is important to avoid injecting air bubbles, which can be mistaken for filling defects.

The pelvicalyceal system and ureter should be adequately opacified but not over distended.

Spot plan film taken And then of opacified pelvicalyceal system and ureter Catheter can be withdrawn to inject contrast in particulur site

of concern Overvigorous injection of contrast may lead to reflux of

contrast into the collecting ducts (pyelotubular reflux) and forniceal rupture with contrast extravasation into the renal sinus (pyelosinus extravasation)

more extensively into the regional lymphatic or veins pyelolymphatic and pyelovenous extravasation.

Ureteropelvic Junction Obstruction

Retrograde ureterogram reveals smooth narrowing and medial shift of the ureter due to Retroperitoneal Fibrosis

Right retrograde pyelogram demonstrates large filling defect in midureter due to transitional cell carcinoma

LoopographyThe standard investigation for ileal conduits is the loopogram

It can be performed in the immediate postoperative period to demonstrate

The integrity of the surgical anastamoses, or later (after months or years) to differentiate between reflux (common) or obstruction

ureteroconduit anastamoses

A Foley catheter (12-16 gauge) is positioned so that its balloon lies a couple of centimeters into the conduit then cautiously inflated so as to produce a reasonable seal without over distending the conduit. Between 20 and 40 ml of contrast is injected under direct screening to outline the conduit, which is normally of the order of 12-15 cm long.

Usually there is free reflux into the ureters and pelvicalyceal systems.

A series of spot films are taken to record this. most important areas to study are the ureteroconduit

anastamoses A rare complication of this procedure in patients

with spinal injuries is the development of severe hypertension (autonomic dysreflexia) due to over distension of the ileal loop.

Loopogram showing the ileal conduit-enteric fistula in patient

Stentography Urologists routinely leave narrow gauge hollow

stents running from the ureters into reconstructed bladders or ileal conduits in the immediate postoperative period.

The stents run to the exterior either via the urethra or a cutaneous stoma.

Stentography is frequently requested to demonstrate the integrity of the distal ureteric anastamoses within a few days of surgery.

procedure 10 and 20 ml 150 strength contrast is injected

under direct screening via each stent in turn, which opacities the upper tracts

followed by drainage around the stents down into the bladder or diversion

Spot films are taken, again paying particular attention to the distal ureteric anastamoses

Cystography

Cystography can be classified into three groups: micturating cystourethrography (MCUG) dynamic cystography simple cystography

Simple cystography• Simple cystography is used to assess the

integrity of the bladder following trauma or surgery

• or to investigate suspected fistulas involving the bladder (usually into the gastrointestinal tract, occasionally elsewhere such as the vagina).

Approximately 250 ml contrast is infused into the bladder

should be done under frequent intermittent screening control so that extravasations can be identified as soon as it occurs.

When the bladder has been filled or when extravasation is identified a spot film is obtained in the supine position. Ideally 45° oblique lateral spot films should be obtained

When a patient has undergone radical prostatectomy

or cystectomy, with preservation of the sphincter and reconstruction of the bladder using small bowel

a cystogram is often performed around 10 days postoperatively to demonstrate the integrity of the surgical anastamoses prior to removal of the urethral catheter.

Urethrography This can be performed via an ascending or

descending approach. Descending urethrography is usually part of

the micturating cystogram and is rarely indicated in adults.

When it is performed in adults the bladder should be adequately filled (with at least 200 ml of contrast).

The screening table should be positioned erect.

Imaging is performed directly anteroposterior in females,45° oblique projection in males

Ascending urethrography is essentially confined to the male. It is used in the investigation of trauma, stricture and fistulas. The patient is positioned in a 45° oblique position dependent hip partly flexed to provide stability and ensure the

urethra is not projected over hone. A 12-16 gauge Foley catheter is positioned with its balloon a

Couple of centimeters into the distal urethra. The balloon is gently partially inflated to provide a seal without

undue trauma

Between 5 and 10 ml 150 strength contrast is injected gently into the urethra under direct screening and spot filets are taken.

The urethra is usually easily opacifed back to the urogenital diaphragm.

In a minority of patients contrast will reflux into the posterior urethra and bladder.

Usually ascending urethrography the prostatic urethra is not demonstrated.

Overenthusiastic instillation of contrast into the urethra can be painful and produce extravasation of contrast into the corpora cavernosa

there is transection of the urethra and extravasation of contrast

Female urethrography is rarely required virtually all urethral pathology being better demonstrated on urethroscopy or transvaginal sonography.

voiding cystourethrogram. The urethra is short indicating this is a female patient.

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